This document summarizes cell division through mitosis and meiosis. It describes the cell cycle phases of interphase and mitosis. Mitosis consists of prophase, metaphase, anaphase and telophase and ensures newly formed cells are identical to the parent cell. Meiosis involves two cell divisions and results in four haploid daughter cells with half the number of chromosomes, allowing for genetic variation. The stages of meiosis I and meiosis II are discussed. Cytokinesis is the final step of cell division where the cytoplasm is partitioned.

1. CHAPTER 5 – CELL DIVISION
FROM 4 BIOLOGY

2. Replace dead cells in body
Unicellular organisms-
Reproduction
Replace damaged and wounded
tissues
Multicellular organisms-Growth
Why do cells divide?

3. CELL CYCLE
Figure above shows all the phases and sub-phases in cell cycle

4. G1 Phase (Growth
phase 1)
• Synthesize of new
organelles and
protein
• Cell grows in size
S Phase (Synthesis
phase)
• Genome is
replicated
• Pair of centrosome
is formed at
cytoplasm
G2 Phase (Growth
phase 2)
• Cell continues to
make protein and
organells and
increase in size
• Prepare for next
phase
INTERPHASE

5. MITOSIS
Mitosis consists of four successive stages, which is prophase, metaphase,
anaphase and telophase. Note that above picture is for animal cells, while
plant cells don’t have centrioles.

6. Importance of controlled
mitosis process
Ensure newly formed
daughter cells are
genetically identical
To parental cell
Checkpoint in each
phases-ensure any
damages in genome
is repaired
Ensure that cell
division occurs only
when necessary (eg -
to repair damaged
tissue)
Ensure cell division
occurs in correct
frequency (different
cell type has
different frequency)

7. What if mitosis is
uncontrolled?
Production of tumour that
may form metastasis
Metastatic tumour may
destroy neighbouring cellsDamaged checkpoint may
result in damaged not
repaired
Porduction of too many cells
that are undifferentiated

8. APPLICATION OF MITOSIS
1. Tissue culture techniques
Figure above shows general tissue culture techniques.

9. 2. Animal cloning
1. The nucleus is removed from the eggs
2. The somatic cell is isolated from donor
3. Using electric shock, the somatic cell is
fused with anucleated egg
4. The fused cells developed into embryo in
vitro before transplanted into foster mother

10. WHAT IS
MEIOSIS???
Occurs in reproductive organs (testes and ovaries
in human)
Number of chromosomes is halved in daughter
cells (haploid)
Two stages – MEIOSIS I AND MEOSIS II

11. Phases of meiosis I
Figure above shows all phases of meiosis I starting from Prophase I, Metaphase I,
Anaphase I, and Telophase I. Meiosis I is followed directly by cytokinesis and meiosis II (no
interstitial interphase gap)

12. Phases meiosis II
Figure above shows all the phases in meiosis II. The processes of meiosis II is similar to
mitosis process, only it yields four daughter cells that have half the number of
chromosomes (equational division)

13. CYTOKINESIS

14. Cytokinesis in animal cells
Actin filaments pull plasma
inwards forming cleavage furrow
Constriction at centre of cell
continues
The cell separated at centre
producing two daughter cells
Figure above reflects the process of cytokinesis in
animal cell

15. Cytokinesis in plant cells
Carbohydrate vesicles gather at
middle cells (between the
The vesicles fuse to from cell
plate
Cell plate form cell wall that
separate two daughter cells
Figure above reflects the process of cytokinesis in
plant cell

16. MITOSIS
VS
MEIOSIS

17. MITOSIS MEIOSIS
Similarities Involve Prophase, Metaphase, Anaphase and
Telophase
Production of new cells
Differences Only one cell division Involves two cell division
No synapsis Synapsis occur
Produce somatic cells Produce gamete cells
No cross over Crossing-over occurs
Produce two diploid
daughter cells
Produce four haploid
daughter cells
Gentically identical
daughter cells
Variation in daughter
cells

18. THANK YOU